Only one way to find out. Some people on craigslist think they can sell their crap for retail and then there are people who are just selling it at cheap prices kinda almost like charity.
I've gotten some real stuff for real cheap on craigslist. I got this new 27" TV along with a progressive scan dvd player and a nice cherry wood TV Stand all for $100. The DVD player alone still sells at Circuit City for $70, let alone the stereo TV and the stand. The guy's grandma just passed away and he just wanted to get rid of it. I also just recently purchased a dye sub photo printer for 1/4 of the price retail, even thought the printer had never been opened (the ink was still sealed) cause the guy was moving to Australia.
So like I said, only one way to find out.